diff --git a/Sources/llama/LlamaRunner.swift b/Sources/llama/LlamaRunner.swift
index 3c652687de9c6..08f8b8d973fe0 100644
--- a/Sources/llama/LlamaRunner.swift
+++ b/Sources/llama/LlamaRunner.swift
@@ -36,7 +36,7 @@ public class LlamaRunner {
     case initializing
     case generatingOutput
     case completed
-    case failed(error: Error)
+    case failed(error: Error?)
   }
 
   public let modelURL: URL
diff --git a/Sources/llamaObjCxx/bridge/LlamaEvent.mm b/Sources/llamaObjCxx/bridge/LlamaEvent.mm
index 880b506e69b57..b1f34a9005f0d 100644
--- a/Sources/llamaObjCxx/bridge/LlamaEvent.mm
+++ b/Sources/llamaObjCxx/bridge/LlamaEvent.mm
@@ -78,7 +78,7 @@ + (instancetype)completed
 
 + (instancetype)failedWithError:(nonnull NSError *)error
 {
-  _LlamaEvent *event = [[_LlamaEvent alloc] initWithEventType:LlamaEventTypeFailed data:{}];
+  _LlamaEvent *event = [[_LlamaEvent alloc] initWithEventType:LlamaEventTypeFailed data:{ .failed_error = error }];
   return event;
 }